Long-term risk of secondary skin cancers after radiation therapy for Hodgkin's lymphoma

Abstract

Purpose: Survivors of Hodgkin's lymphoma (HL) are at risk of secondary tumors. We investigated the risk of secondary skin cancers after radiotherapy compared to treatment without radiation and to an age-matched population.

Material and methods: We conducted a retrospective cohort study of 889 HL patients treated between 1965 and 2005. Data on secondary skin cancers and treatment fields were retrieved. Incidence rates were compared to observed rates in the Dutch population.

Results: 318 skin cancers were diagnosed in 86 patients, showing significantly higher risks of skin cancers, the majority being BCC. The standardized incidence ratio (SIR) of BCC in HL survivors was significantly increased (SIR 5.2, 95% CI 4.0-6.6), especially in those aged <35 years at diagnosis (SIR 8.0, 95% CI 5.8-10.7). SIR increased with longer follow-up to 15.9 (95% CI 9.1-25.9) after 35 years, with 626 excess cases per 10,000 patients per year. Most (57%) skin cancers developed within the radiation fields, with significantly increased risk in patients treated with radiotherapy compared to chemotherapy alone (p=0·047, HR 2·75, 95% CI 1·01-7.45).

Conclusion: Radiotherapy for HL is associated with a strongly increased long-term risk of secondary skin cancers, both compared to the general population and to treatment with chemotherapy alone.

Keywords: Hodgkin’s lymphoma; Radiation therapy; Secondary cancers; Skin cancers.